1. Field of the Invention
The invention relates to a pulper for pulverizing and suspending paper stock and, more particularly, a pulper having a container which is configured to mix the paper stock with water, and pulverize and suspend the paper stock so as to form a suspension containing paper stock.
2. Discussion of Background Information
Pulpers are used mainly to put air-dry cellulose material or recovered paper into suspension. A pulper includes a container for the suspension of the paper stock, as well as a rotor (e.g., mixing and pulverizing) and, in many cases, a wire in the base area through which the suspension can be pumped off. In use, the charged material, typically in large pieces, webs or pressed bales, is forcefully mixed with water in the pulper by use of the mixing and pulverizing rotor.
A cylindrical container standing vertically with a rotor in the base area has established itself as the standard type for a pulper. In the container, water and the stock to be slushed are added from above and a funnel flow is generated in the suspension with the aid of the rotor. The suspension is suctioned downward by the rotor, in the central area, and is pressed radially outward in the base area, from which a rotational flow results.
Flow measures are also known to control the rotational flow. For example, the circumferential flow is slowed through corresponding flow installations (baffle plates) on the container wall, since it makes only a slight contribution to the slushing. In contrast, supporting the actual rotation, i.e., the repeated transport of the stock to be slushed into the rotor area brings about an improvement of the slushing effect. The aim is also to draw the freshly charged stock into the suspension as quickly as possible. For these reasons a great deal of development has already been carried out on the rotors and containers of the pulpers.
Attempts have been made to optimize the pulpers to achieve a quick slushing that is economical in terms of power. For example, it has been proposed in DE 197 01 129 A1 to design the container of the pulper in an angular manner to improve the stock intake. The asymmetrical arrangement of the rotor was intended to provide another improvement. However, this pulper has not been widely used.
Another attempt to improve pulpers is shown in DE 36 38 993 C2. In this attempt to improve the pulper, the flow of the suspension is generated with the aid of a laterally mounted rotor. The oblique position of the rotor axis also has been carried out, e.g., with a pulper shown in DE 32 24 705 C2, in which a rotor built relatively high has an acute angle to the vertical axis.
To improve the rotation, unconventional approaches have also been taken, such as, e.g., in DE 34 29 514 C2. According to DE 34 29 514 C2, a plurality of complex rotors are provided within the same pulper container.